Harper screenshot

Harper

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Updated: 16 Jan 2026
9091 Stars

Offline, privacy-first grammar checker. Fast, open-source, Rust-powered

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Overview

Harper is an innovative offline grammar checker designed with a strong focus on privacy. Built with Rust, it offers a fast and efficient experience that sets it apart from other grammar checkers that often rely on cloud services. This open-source tool is an excellent choice for those who value both speed and data security, allowing users to check their writing without compromising their personal information.

With Harper, you can enjoy the freedom of editing and improving your writing skills while staying in full control of your data. The seamless offline functionality makes it suitable for use in various environments, where internet access may be limited or not preferred.

Features

  • Privacy-First Approach: Harper ensures user data remains private by processing all checks locally without sending information over the internet.

  • Offline Functionality: No internet connection? No problem! Harper works completely offline, making it a reliable option anywhere.

  • Open-Source: Being open-source allows users to inspect, modify, and contribute to the software, fostering a community-driven development environment.

  • Fast Performance: Powered by Rust, Harper delivers quick grammar checks, enhancing productivity without interrupting the writing process.

  • User-Friendly Interface: The tool features an intuitive interface that makes it easy for writers of all skill levels to navigate and use effectively.

  • Customizable Options: Users can tailor the grammar checking settings to fit their personal writing style and preferences, ensuring more relevant suggestions.

  • Regular Updates: As an open-source project, Harper benefits from regular updates and improvements contributed by the community, maintaining its effectiveness and relevance in the ever-evolving landscape of writing tools.